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Multiple action sites of ultrasound on escherichia coli and Staphylococcus aureus

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Food Science and Human Wellness 2018年第1期7卷 102-109页

作者： Xinyu Liao Jiao Li Yuanjie Suo Shiguo Chen Xingqian Ye Donghong Liu Tian Ding Department of Food Science and Nutrition National Engineering Laboratory of Intelligent Food Technology and EquipmentZhejiang UniversityHangzhouZhejiang 310058China Key Laboratory for Agro-Products Postharvest Handling of Ministry of Agriculture Zhejiang Key Laboratory for Agro-Food ProcessingHangzhouZhejiang 310058China Fuli Institute of Food Science Zhejiang UniversityHangzhou 310058China

Ultrasound,is thought to a potential non-thermal sterilization technology in food ***,the exact mechanisms underlying microbial inactivation by ultrasound still remain *** this study,the action modes of ultrasound on both Gram-negative and Gram-positive microorganisms were *** colony results,ultrasound acted as an irreversible effect on both Eshcerichia coli and Staphylococcus aureus without sublethal *** result in this study also showed that a proportion of bacteria subpopulation suffered from serious damage of intracellular components(*** and enzymes)but with intact cell *** speculated that the inactivated effects of ultrasound on microbes might more than simply completed disruption of cell *** microbial cells who had not enter the valid area of ultrasonic cavitation might be injected with free radicals produced by ultrasound and experienced interior injury with intact exterior structure,and others who were in close proximity to the ultrasonic wave field would be immediately and completely disrupted into debris by high power mechanic *** findings here try to provide extension for the inactivation mechanisms of ultrasound on microorganisms.

关键词： Ultrasound Inactivation mechanism Reactive oxygen species(ROS) Staphylococcus aureus escherichia coli

The Effect of Air Plasma on Sterilization of escherichia coli in Dielectric Barrier Discharge

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Plasma Science and Technology 2012年第8期14卷 735-740页

作者：胡淼郭赟 College of Nuclear Science and Technology Harbin Engineering University

In this work, a Dielectric Barrier Discharge （DBD） air plasma was used to sterilize escherichia eoli （E. coli） on the surface of medical Polyethylene Terephthalate （PET） film. The leakage of cellular DNA and protein by optical absorbance measurement at 260 nm and 280 nm, together with transmission electron microscopy （TEM） about cell morphology were performed after sterilization to analyse inactivation mechanisms. The results indicated that the DBD air plasma was very effective in E. coli sterilization. The plasma germicidal efficiency depended on the plasma treatment time, the air-gap distance, and the applied voltage. Within 5 min of plasma treatment, the germicidal efficiency against E. coli could reach 99.99%. An etching action on cell membranes by electrons, ions and radicals is the primary mechanism for DBD air plasma sterilization, which leads to the effusion of cellular contents （DNA and protein） and bacterial death.

关键词： DBD air plasma escherichia coli PET sterilization

Chemical Synthesis of Copper Nanospheres and Nanocubes and Their Antibacterial Activity Against escherichia coli and Enterococcus sp.

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Acta Metallurgica Sinica(English Letters) 2017年第1期30卷 29-35页

作者： A.Alshareef K.Laird R.B.M.Cross Faculty of Technology School of Engineering and Sustainable DevelopmentEmerging Technologies Research CentreDe Montfort UniversityLeicester LE1 9BHUK Faculty of Health and Life Sciences Leicester School of PharmacyDe Montfort UniversityLeicester LE1 9BHUK

The interest in synthesising inorganic nanomaterials for biological applications has increased in recent years, especially for antibacterial purposes. In the present study, spherical and cube-shaped copper nanoparticles were synthesised by a chemical reduction method and their efficacy as anfimicrobial agents against both Gram-negative （escherichia coli） and Gram-positive （Enterococcus sp.） organisms investigated. The nanoparticles were characterised using ultraviolet/ visible spectroscopy, scanning electron microscopy, energy-dispersive spectroscopy and X-ray diffraction. Copper nanocubes were found to be more antimicrobial when compared with copper nanospheres, and it is postulated that whilst both sets of nanoparticles have similar total surface areas, the different shapes have different active facets and surface energies, which may lead to differing bactericidal behaviour.

关键词： Copper nanoparticles Scanning electron microscopy (SEM) Antibacterial escherichia coli Enterococcus sp.

escherichia coli Producing CTX-M and DHA-1 Beta-lactamases in Farm Animals in Chongqing City of China

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畜牧兽医学报 2010年第S1期41卷 97-101页

作者： WU Jun-wei ZHANG Zhen-zhen WANG Kai-yu College of Animal Medicine Sichuan Agricultural UniversityYa’an 625014China Department of Veterinary Medicine Southwest UniversityRongchang 402460China

Aim of this study was to investigate the genotypic distribution of extended-spectrum β-lactamases (ESBLs) and AmpC enzymes among escherichia coli isolated from farm animals in Chongqing City. 326 *** isolates were obtained from piglets,cattle and *** these isolates,19 ESBLs and 6 AmpC-producing *** isolates were detected by preliminary screening and phenotypic identification, and polymerase chain reaction and sequence analysis methods were used to detect ESBLs and AmpCβ-lactamases *** results showed that the frequencies of TEM,CTX-M,DHA-1 and CMY-2 genes were 2.15%,5.21%,0.61%and 0.61%,respectively,in *** of animal origin in the Chongqing area,and 5 *** isolates were found to carry two kinds of *** DHA-1 gene was detected for the first time in a veterinary clinic in China;its GenBank accession number is *** study indicated that TEM and CTX-M genes were the predominant genotypes in Chongqing,and the majority of ESBLs and AmpC-producing *** isolates were multi-resistant to antibiotics,so they deserve particular attention in veterinary clinics.

关键词： escherichia coli farm animals CTX-M DHA-1 China

A Study of Mutation Breeding of High-Yielding Tryptophanase escherichia coli by Low-Energy N^+ Ion Beam Implantation

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Plasma Science and Technology 2009年第6期11卷 744-749页

作者：庞敏姚建铭王冬梅 Key Laboratory of Ion Beam Bio-engineering of Institute of Plasma Physics Chinese Academy of Sciences Hefei Research Center of Ion Beam Engineering and Technology

Low energy ion beam has been widely applied in microbe breeding, plant breeding, gene transfer and cell modification. In this study, the escherichia coli （***） strain producing tryptophanase was irradiated by a low energy nitrogen ion beam with an energy of 10 keV at a fluence of 13 × 10^14 N^＋/cm^2 when glycerin at a 15% concentration was used as a protector. The effect on the biomass of E. coli after N^＋ implantation was analyzed in detail by statistic methods. The screening methods used in this study were proven to be effective. After continuous mutagenicity, a high-yield tryptophanase strain was selected and both its biomass and enzymatic activity were higher than those of the parent strain. The results of scale-up production showed that the biomass could reach wet weight 8.2 g/L and 110 g L-tryptophan could be formed in the volume of the 1 l enzymatic reaction system.

关键词： ion implantation L-tryptophan escherichia coli breeding

Dissociation of outer membrane for escherichia coli cell caused by cerium nitrate

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Journal of Rare Earths 2010年第2期28卷 312-315页

作者：陈爱美施庆珊冯劲欧阳友生陈仪本谭绍早 Guangdong Institute of Microbiology Guangdong Open Laboratory of Applied Microbiology Guangdong Province Key Laboratory of Microbial Culture Collection and Application Department of Chemistry Jinan University

The biological effect of cerium nitrate on the outer membrane(OM) of escherichia coli(***) cell was studied,and the antim-icrobial mechanism of rare earth elements was *** antimicrobial effect of cerium nitrate on *** cell was valued by plate count method,and the morphology change of *** cell was observed with scanning electron microscopy(SEM) and transmission electron microscopy(TEM).The results showed that the *** cell suspension was flocculated when the concentration of Ce(NO3)3?6H2O...

关键词： cerium nitrate escherichia coli outer membrane scanning electron microscope transmission electron microscope morphology rare earths

Next-generation probiotic candidates targeting intestinal health in weaned piglets: Both live and heat-killed Akkermansia muciniphila prevent pathological changes induced by enterotoxigenic escherichia coli in the gut

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Animal Nutrition 2024年第2期17卷 110-122页

作者： Cong Lan Hua Li Yuqing Shen Yang Liu Aimin Wu Jun He Jingyi Cai Gang Tian Xiangbing Mao Zhiqing Huang Bing Yu Ping Zheng Jie Yu Junqiu Luo Hui Yan Yuheng Luo Key Laboratory for Animal Disease-Resistance Nutrition of Ministry of Education of China Key Laboratory for Animal Disease-Resistance Nutrition and Feed of Ministry of Agriculture of ChinaKey Laboratory of Animal Disease-Resistant Nutrition of Sichuan ProvinceEngineering Research Center of Animal Disease-Resistance Nutrition Biotechnology of Ministry of Education of ChinaAnimal Nutrition InstituteSichuan Agricultural University

The use of next-generation probiotics （NGP） in pigs for combating diseases has been subject to limited *** we explored the potential of a well-known NGP candidate Akkermansia muciniphila targeting pig gut *** the first screening experiment,we found that the abundance of *** peaked at 14 d old but decreased at weaning （21 d old;Pescherichia coli （ETEC） group,and all groups except CON received a 5-d ETEC *** supplementation of *** numerically reduced the diarrhea rate of weaned pigs compared to the pigs that only received the ETEC challenge （P=0.57）,but the LIA group had a higher diarrhea rate than the CON group （P<0.05）.Consistent with this,the supplementation of *** improved the small intestinal morphology and structure,proportion of CD4+T lymphocytes in the blood,as well as the expression of genes related to intestinal barrier and antioxidant indices of pigs with ETEC challenge,especially for the LA group （P<0.05）.Meanwhile,*** supplementation reduced the expression of ETEC virulence factor genes in the ileum and colon of pigs challenged by ETEC （P<0.05）.Therefore,*** may protect the intestinal health of weaned piglets from damage caused by

关键词： Akkermansia muciniphila Weaned piglet Enterotoxigenic escherichia coli challenge Intestinal health

Construction of an engineered escherichia coli for effective synthesis of 2'-fucosyllactose via the salvage pathway

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Synthetic and Systems Biotechnology 2024年第1期9卷 108-114页

作者： Shanquan Liang Zi He Dan Liu Shaoqing Yang Qiaojuan Yan Zhengqiang Jiang College of Food Science and Nutritional Engineering China Agricultural UniversityBeijing100083China Food Laboratory of Zhongyuan Luohe462300HenanChina College of Engineering China Agricultural UniversityBeijing100083China

2'-Fucosyllactose(2'-FL)is one of the important functional oligosaccharides in breast *** far,few attempts on biosynthesis of 2'-FL by the salvage pathway have been ***,the salvage pathway enzyme genes were introduced into the *** BL21star(DE3)for synthesis of 2'-*** 2'-FL titer increased from 1.56 to 2.13 g/L by deleting several endogenous genes on competitive ***α-1,2-fucosyltransferase(WbgL)was selected,and improved the 2'-FL titer to 2.88 g/***,the expression level of pathway enzyme genes was tuned through optimizing the plasmid copy ***,the spatial distribution of WbgL was enhanced by fusing with the MinD *** optimizing the fermentation conditions,the 2'-FL titer reached to 7.13 g/*** final strain produced 59.22 g/L of 2'-FL with 95%molar conversion rate of lactose and 92% molar conversion rate of fucose in a 5 L *** findings will contribute to construct a highly efficient microbial cell factory to produce 2'-FL or other HMOs.

关键词： 2'-fucosyllactose Human milk oligosaccharides escherichia coli Fed-batch fermentation Salvage pathway

Expression in escherichia coli of Three Different Soybean Late Embryogenesis Abundant （LEA） Genes to Investigate Enhanced Stress Tolerance

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Journal of Integrative Plant Biology 2005年第5期47卷 613-621页

作者： YingLAN DanCAI Yi-ZhiZHENG InstituteofGeneticsandCytology SchoolofLifeSciencesNortheastNormalUniversityChangchun130021China／／MedicalCollegeofBeihuaUniversityJilin132021China CollegeofLifeSciences KeyLaboratoryofMicroorganismandGeneticEngineeringofShenzhenCityShenzhenUniversityShenzhen518060China

Abstract: In order to identify the function of late embryogenesis abundant (LEA) genes, in vitro functional analyses were performed using an escherichia coli heterologous expression system. Three soybean late embryogenesis abundant (LEA) genes, PM11 (GenBank accession No. AF004805; group 1), PM30 (AF117884; group 3), and ZLDE-2 (AY351918; group 2), were cloned and expressed in a pET-28a system. The gene products were separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and identified by mass spectrometry. E. coli cells containing the recombinant plasmids or empty vector as controls were treated by salt and low temperature stress. Compared with control cells, the E. coli cells expressing either PM11 or PM30 showed a shorter lag period and improved growth when transferred to LB (Luria-Bertani) liquid media containing 800 mmol/L NaCl or 700 mmol/L KCl or after 4°C treatment. E. coli cells expressing ZLDE-2 did not show obvious growth improvement both in either high KCl medium or after 4°C treatment. The results indicate that the E. coli expression system is a simple, useful method to identify the functions of some stress-tolerant genes from plants.

关键词： escherichia coli gene expression LEA gene osmotic stress salt stress soybean